As oil-based ink compositions for ball-point pens, many oil-based ink compositions for ball-point pens using, as coloring agents, various dyes such as nigrosine-based dyes, basic dyes, and acid dyes as well as types of dyes, in which the various dyes have been processed, have been conventionally proposed.
Various coloring agents have been used in such oil-based ink compositions for ball-point pens, an oil-based ink composition for a ball-point pen using a nigrosine-based dye is disclosed in Patent Literature 1 (Title of the Invention: “OIL-BASED BLACK INK”), an oil-based ink composition for a ball-point pen using a salt-forming dye of a triarylmethane-based basic dye and an azo yellow acid dye is disclosed in Patent Literature 2 (Title of the Invention: “OIL-BASED BLACK INK”) or Patent Literature 3 (Title of the Invention: “OIL-BASED BLACK INK”), and an oil-based ink composition for a ball-point pen using a salt-forming dye based on a basic dye is disclosed in Patent Literature 4 (Title of the Invention: “OIL-BASED BLACK INK COMPOSITION FOR BALL-POINT PEN”) or the like.